File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PDB file extension

Program Database

Database Files

SITX file extension

StuffIt X Archive

Compressed Files

LOG file extension

Log File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

GADGET file extension

Windows Gadget

Executable Files

PAGES file extension

Pages Document

Text Files

JAVA file extension

Java Source Code File

Developer Files

IFF file extension

Interchange File Format

Audio Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

MOV file extension

Apple QuickTime Movie

Video Files

SDF file extension

Standard Data File

Data Files

TEX file extension

LaTeX Source Document

Text Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

7Z file extension

7-Zip Compressed File

Compressed Files